Determining the Efficacy of the SACS in Identifying Preschoolers with ASDs: Development of the SACS-Preschool (SACS-Pr)

Background: The Social Attention and Communication Study (SACS; Barbaro & Dissanayake, 2010) adopted a developmental surveillance framework for the prospective identification of Autism Spectrum Disorders (ASDs) in infants and toddlers. This involved repeated monitoring of the early markers of ASDs at children’s 12-, 18-, and 24-month routine health check-ups in a community-based setting. A follow-up diagnostic assessment was conducted at 48-months. Although the overall psychometric properties of the SACS were excellent, not all children later diagnosed with ASDs were identified as ‘at risk’ by 24-months. Thus, an additional SACS assessment during the preschool period may prove useful in the identification of children with ASDs who are not identified by 24-months.

Objectives: The aim in the current study was to: 1) develop a preschool version of the SACS to be added to the existing SACS framework; and to 2) identify the most predictive behavioural markers of ASDs on the SACS-Pr, which can effectively discriminate between preschoolers with and without ASDs.

Methods: The SACS-Preschool (SACS-Pr) was developed based on the original 24-month SACS checklist, and contains 22 behavioural items modified to reflect the developmental milestones of preschool aged children. An additional section, Repetitive, Stereotyped and Sensory Behaviours/Interests (RSSBIs), was added to reflect the emergence of these behaviours in the preschool period. A coder, blind to diagnostic status, observed video footage of the SACS follow-up assessments at 48-months (n = 77) and completed the SACS-Pr checklist for each child. Inter-rater reliability for each individual item, and the total checklist, was excellent. Follow-up assessments included administration of the Autism Diagnostic Observation Schedule and the Mullen Scales of Early Learning to 53 preschoolers with ASDs (Mean Age = 49.7 months) , and 24 with Developmental and/or Language Delay (Mean Age = 47.1 months).

Results: Consistent with the original SACS results, the current study found that Eye Contact, Pointing and Showing continue to be key markers for the identification of ASDs in preschoolers. Additionally, Social Smile, Follows Two Unrelated Commands, Reciprocal Social Interaction and Odd/Unusual Speech were also identified as key markers of ASDs. Logistic regression analyses revealed that the best group of predictors for a diagnostic classification of ASD contained all of these key markers, with the omission of Social Smile and the addition of Pretend Play. Follow-up Receiver-Operating-Characteristic (ROC) analyses showed that this model, containing all eight variables, effectively discriminated between children with and without ASDs, with an excellent Area-Under-the-Curve value of 0.95.

Conclusions: The SACS-Pr was found to effectively discriminate between preschoolers with and without ASDs, in a referred sample. The behavioural items Eye Contact, Pointing, and Showing, found to be key markers of ASDs in infants and toddlers in the original SACS, continue to be key markers in preschoolers with ASDs, reinforcing the importance of repeated monitoring of these critical joint attention behaviours. The use of the SACS-Pr, alongside the original SACS, is currently being trialled in a community-based setting to determine its usefulness in the identification of preschoolers with ASDs in a low-risk sample.